The present invention has referred a Disclosure Document No. 583370 on Aug. 4, 2005.
1. Field of the Invention
The present invention relates generally to an antenna, and more particularly to a multi-band antenna used in a portable electronic device.
2. Description of the Prior Art
With the development of wireless communication, more and more portable electronic devices, such as a notebook, install an antenna system for working in a Wireless Local-area Network (WLAN). Transmitting and receiving signals plays an important role in wireless communication process. In recent years, a majority of WLAN bases on Bluetooth technical standard or 802.11 technical standard. Antenna in Bluetooth technical standard is based on 2.4 GHz frequency band, and in 802.11 technical standard is based on 2.4 GHz and 5 GHz. So, antenna in notebook mostly works at the above frequency bands at the present time.
PIFA (Planar Inverted-F Antenna) is a kind of minitype antenna usually used in the portable electronic devices. PIFA has compact structure, light weight, perfect impedance match, desired horizontal polarization and vertical polarization, and is easy to achieve multi-band. So, more and more PIFAs are used in the portable electronic devices.
However, the feeding point of an ordinary PIFA is difficult to achieve. In other words, the feeding line of the PIFA is difficult to be soldered at the feeding point according to calculation. For example, U.S. Pat. No. 6,861,986 B2 discloses a PIFA comprising a radiating element, a connecting element, a grounding element, a feeding point on the connecting element and a feeding line. The feeding line of the PIFA is difficult to be soldered at the feeding point according to calculation because there is no mark on the location of the feeding point on the connecting element, thus, the accurate soldering between the feeding line and the PIFA is hard to achieve. Accordingly, the input impedance of the PIFA is likely to do not match with the impedance of the feeding line.
Hence, in this art, a multi-band antenna to overcome the above-mentioned disadvantages of the prior art will be described in detail in the following embodiment.